x86: microcode: use smp_call_function_single instead of set_cpus_allowed, cleanup of synchronization logic

* Solve issues described in 6f66cbc63081fd70e3191b4dbb796746780e5ae1
  in a way that doesn't resort to set_cpus_allowed();

* in fact, only collect_cpu_info and apply_microcode callbacks
  must run on a target cpu, others will do just fine on any other.
  smp_call_function_single() (as suggested by Ingo) is used to run
  these callbacks on a target cpu.

* cleanup of synchronization logic of the 'microcode_core' part

  The generic 'microcode_core' part guarantees that only a single cpu
  (be it a full-fledged cpu, one of the cores or HT)
  is being updated at any particular moment of time.

  In general, there is no need for any additional sync. mechanism in
  arch-specific parts (the patch removes existing spinlocks).

  See also the "Synchronization" section in microcode_core.c.

* return -EINVAL instead of -1 (which is translated into -EPERM) in
  microcode_write(), reload_cpu() and mc_sysdev_add(). Other suggestions
  for an error code?

* use 'enum ucode_state' as return value of request_microcode_{fw, user}
  to gain more flexibility by distinguishing between real error cases
  and situations when an appropriate ucode was not found (which is not an
  error per-se).

* some minor cleanups

Thanks a lot to Hugh Dickins for review/suggestions/testing!

   Reference: http://marc.info/?l=linux-kernel&m=124025889012541&w=2

[ Impact: refactor and clean up microcode driver locking code ]

Signed-off-by: Dmitry Adamushko <dmitry.adamushko@gmail.com>
Acked-by: Hugh Dickins <hugh@veritas.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andreas Herrmann <andreas.herrmann3@amd.com>
Cc: Peter Oruba <peter.oruba@amd.com>
Cc: Arjan van de Ven <arjan@infradead.org>
LKML-Reference: <1242078507.5560.9.camel@earth>
[ did some more cleanups ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
 arch/x86/include/asm/microcode.h  |   25 ++
 arch/x86/kernel/microcode_amd.c   |   58 ++----
 arch/x86/kernel/microcode_core.c  |  326 +++++++++++++++++++++-----------------
 arch/x86/kernel/microcode_intel.c |   92 +++-------
 4 files changed, 261 insertions(+), 240 deletions(-)

(~20 new comment lines)

1 files changed, 22 insertions, 36 deletions

diff --git a/arch/x86/kernel/microcode_amd.c b/arch/x86/kernel/microcode_amd.c
index 453b5795a5c6..c8be20f16447 100644
--- a/arch/x86/kernel/microcode_amd.c
+++ b/arch/x86/kernel/microcode_amd.c
@@ -13,25 +13,13 @@
  *  Licensed under the terms of the GNU General Public
  *  License version 2. See file COPYING for details.
  */
-#include <linux/platform_device.h>
-#include <linux/capability.h>
-#include <linux/miscdevice.h>
 #include <linux/firmware.h>
-#include <linux/spinlock.h>
-#include <linux/cpumask.h>
 #include <linux/pci_ids.h>
 #include <linux/uaccess.h>
 #include <linux/vmalloc.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
-#include <linux/mutex.h>
-#include <linux/sched.h>
-#include <linux/init.h>
-#include <linux/slab.h>
-#include <linux/cpu.h>
 #include <linux/pci.h>
-#include <linux/fs.h>
-#include <linux/mm.h>
 
 #include <asm/microcode.h>
 #include <asm/processor.h>
@@ -79,9 +67,6 @@ struct microcode_amd {
 #define UCODE_CONTAINER_SECTION_HDR     8
 #define UCODE_CONTAINER_HEADER_SIZE     12
 
-/* serialize access to the physical write */
-static DEFINE_SPINLOCK(microcode_update_lock);
-
 static struct equiv_cpu_entry *equiv_cpu_table;
 
 static int collect_cpu_info_amd(int cpu, struct cpu_signature *csig)
@@ -144,9 +129,8 @@ static int get_matching_microcode(int cpu, void *mc, int rev)
         return 1;
 }
 
-static void apply_microcode_amd(int cpu)
+static int apply_microcode_amd(int cpu)
 {
-        unsigned long flags;
         u32 rev, dummy;
         int cpu_num = raw_smp_processor_id();
         struct ucode_cpu_info *uci = ucode_cpu_info + cpu_num;
@@ -156,25 +140,25 @@ static void apply_microcode_amd(int cpu)
         BUG_ON(cpu_num != cpu);
 
         if (mc_amd == NULL)
-                return;
+                return 0;
 
-        spin_lock_irqsave(&microcode_update_lock, flags);
         wrmsrl(MSR_AMD64_PATCH_LOADER, (u64)(long)&mc_amd->hdr.data_code);
         /* get patch id after patching */
         rdmsr(MSR_AMD64_PATCH_LEVEL, rev, dummy);
-        spin_unlock_irqrestore(&microcode_update_lock, flags);
 
         /* check current patch id and patch's id for match */
         if (rev != mc_amd->hdr.patch_id) {
                 printk(KERN_ERR "microcode: CPU%d: update failed "
                        "(for patch_level=0x%x)\n", cpu, mc_amd->hdr.patch_id);
-                return;
+                return -1;
         }
 
         printk(KERN_INFO "microcode: CPU%d: updated (new patch_level=0x%x)\n",
                cpu, rev);
 
         uci->cpu_sig.rev = rev;
+
+        return 0;
 }
 
 static int get_ucode_data(void *to, const u8 *from, size_t n)
@@ -263,7 +247,8 @@ static void free_equiv_cpu_table(void)
         }
 }
 
-static int generic_load_microcode(int cpu, const u8 *data, size_t size)
+static enum ucode_state
+generic_load_microcode(int cpu, const u8 *data, size_t size)
 {
         struct ucode_cpu_info *uci = ucode_cpu_info + cpu;
         const u8 *ucode_ptr = data;
@@ -272,12 +257,13 @@ static int generic_load_microcode(int cpu, const u8 *data, size_t size)
         int new_rev = uci->cpu_sig.rev;
         unsigned int leftover;
         unsigned long offset;
+        enum ucode_state state = UCODE_OK;
 
         offset = install_equiv_cpu_table(ucode_ptr);
         if (!offset) {
                 printk(KERN_ERR "microcode: failed to create "
                        "equivalent cpu table\n");
-                return -EINVAL;
+                return UCODE_ERROR;
         }
 
         ucode_ptr += offset;
@@ -312,28 +298,27 @@ static int generic_load_microcode(int cpu, const u8 *data, size_t size)
                         pr_debug("microcode: CPU%d found a matching microcode "
                                  "update with version 0x%x (current=0x%x)\n",
                                  cpu, new_rev, uci->cpu_sig.rev);
-                } else
+                } else {
                         vfree(new_mc);
-        }
+                        state = UCODE_ERROR;
+                }
+        } else
+                state = UCODE_NFOUND;
 
         free_equiv_cpu_table();
 
-        return (int)leftover;
+        return state;
 }
 
-static int request_microcode_fw(int cpu, struct device *device)
+static enum ucode_state request_microcode_fw(int cpu, struct device *device)
 {
         const char *fw_name = "amd-ucode/microcode_amd.bin";
         const struct firmware *firmware;
-        int ret;
-
-        /* We should bind the task to the CPU */
-        BUG_ON(cpu != raw_smp_processor_id());
+        enum ucode_state ret;
 
-        ret = request_firmware(&firmware, fw_name, device);
-        if (ret) {
+        if (request_firmware(&firmware, fw_name, device)) {
                 printk(KERN_ERR "microcode: failed to load file %s\n", fw_name);
-                return ret;
+                return UCODE_NFOUND;
         }
 
         ret = generic_load_microcode(cpu, firmware->data, firmware->size);
@@ -343,11 +328,12 @@ static int request_microcode_fw(int cpu, struct device *device)
         return ret;
 }
 
-static int request_microcode_user(int cpu, const void __user *buf, size_t size)
+static enum ucode_state
+request_microcode_user(int cpu, const void __user *buf, size_t size)
 {
         printk(KERN_INFO "microcode: AMD microcode update via "
                "/dev/cpu/microcode not supported\n");
-        return -1;
+        return UCODE_ERROR;
 }
 
 static void microcode_fini_cpu_amd(int cpu)